The present disclosure relates to image forming apparatuses and particularly relates to a technique for improving image quality and preventing toner scattering in an image forming apparatus of a transfer belt type.
Electrophotographic image forming apparatuses, such as a multifunction peripheral, a printer, a copier, and a facsimile device, include those of a transfer belt type in which an endlessly traveling dielectric belt is used to convey a recording paper sheet and transfer a toner image to the recording paper sheet. The image forming apparatus of the transfer belt type is configured to induce electric charges on the surface of the transfer belt to electrostatically attract a recording paper sheet to the transfer belt, convey it in this state, and allow a toner image formed on the surface of a photosensitive drum to be transferred to the recording paper sheet.
The image forming apparatus of the transfer belt type is advantageous in terms of separability of the recording paper sheet from the photosensitive drum (image carrier), stability of sheet conveyance, and image transferability. However, the image forming apparatus of this type may cause separation discharge upon curvature-induced separation of the recording paper sheet from the downstream end of the transfer belt, so that toner on the surface of the recording paper sheet may scatter, resulting in a problem of the occurrence of an image defect (electrostatically toner-scattered image) and a problem in that scattered toner is accumulated in the apparatus to contaminate the apparatus interior. Furthermore, the recording paper sheet is strongly charged to the same polarity as the toner, which presents a problem of the occurrence of electrostatic offset in the fixing process.
As a solution to the above problems, a technique is known in which a high-resistance, sheet-shaped transfer exit guide plate is provided downstream of the transfer belt in the direction of conveyance of the recording paper sheet to eliminate the static electricity of the recording paper sheet separated by curvature from the transfer belt using the guide plate and thus prevent separation discharge of the recording paper sheet.